St. Sophia Museum (Open everyday except Friday)
This ancient basilica, built by Constantine the Great in the 4th century and reconstructed by Justinian in the 6th century, is one of the architectural marvels of all time. Its immense dome rises 55 meters above the ground and 31 meters in diameter. The beautiful decorations include stunning Byzantine mosaics.

Topkapi Imperial Palace (Open everyday except Tuesday)
Overlooking The Bosphorus and the Marmara Sea stands a maze of buildings that was once the great palace of the Ottoman sultans from the 15th to the 19th centuries. The first courtyard is a magnificient wooden garden. To the right of the second court, shaded by cypress and plane trees is the place kithen, now housing an exquisite collection of crystal, silver, and Chinese porcelain, while on the left is Harem, the secluded quarters of the wives and concubines of the sultan. The third court contains the Audience Hall of the Sultan, the library of the Sultan Ahmet the 3rd, an exhibition of robes worn by the sultans and their families, the fanous jewel of the Imperial Treasury and finally, an exhibition of miniatrues. In the center of the third court is the Pavillion of the Holy Mantle, enshrining relics of the Prophet Mohammed.

Hippodrome
In front of the Blue Mosque is the site of the ancient Hippodrome, the scene of chariot races and the center of Byzantine civic life. Of the monuments which once adorned only three remain: the Obelisk of Theodosius, the bronze Serpentine Column and the Column os Constantine. Remains from the curved end of the Hippodrome wall can be seen to the south of these three monuments. Today, it's center of historical, cultural and touristic activities. The square with its surrounding area resembles an open-air museum.

Basilica Cistern (Openeveryday except Monday)
Close to St. Sophia is the 6th century Byzantine cistern known as the Yerebatan Sarnici. Fine brick vaulting is supported by 336 Corithian co.

Archeological Museums (Open everyday except Monday)
These are situated on the perimeter of the first court of Topkapi Palace. The very rich collection of classical antiquities in the Archeological Museum includes the celebrated Alexander Sarcophagus, and the Athena Temple from Assos. The Museum of the Ancient Orient displays antiquities from the Sumerian, Babylonian, Assyrian, Hatti and Hittite civilizations.